Week 2 - An Infection Model Flashcards
1
Q
Describe a model of infection
A
Pathogen + patient –> infection –> infection –> management –> outcome
2
Q
What patient variations can affect infection?
A
- Place: current, recent
- Time: calendar, relative
- Person: gender, age, physiological state, pathological state, social factors
3
Q
What are the different mechanisms of infection?
A
- Contiguous (direct) spread
- Inoculation (e.g. trauma/violence with infected object)
- Haematogenous (spread via bloodstream)
- Ingestion
- Inhalation
- Vector
- Vertical transmission
4
Q
Give an example of a disease for each mechanism of infection
A
- Contiguous spread: salmonella
- Inoculation: tetanus
- Haematogenous: infective endocarditis
- Ingestion: cholera
- Inhalation: common cold
- Vector: malaria
- Vertical transmission: HIV
5
Q
How do you treat infection?
A
Specific: - Antimicrobials - Surgery (drainage, debridement, dead space removal) Supportive: - Symptom relief - Physiological restoration
6
Q
How can antibacterials be classified?
A
- Spectrum (broad or narrow)
- Bactericidal or bacteriostatic
- Chemical structure
- Target site (mechanism of injury)
7
Q
What different antimicrobials are there? (broadly speaking)
A
- Antibacterials
- Antifungal
- Antiviral
- Antiprotozoal
8
Q
What are the ideal features of antibacterials?
A
- Few adverse affects
- Oral/IV
- Can reach site of infection
- Long half life
- Selectively toxic
- No interference with other drugs
9
Q
What are some different mechanisms of action of antibacterials?
A
Interfere with:
- Cell wall synthesis
- Protein synthesis
- Nucleic acid synthesis
- Cell membrane function (rare)
10
Q
What are the mechanisms of drug resistance?
A
- Drug resistant enzymes (produced by bacteria)
- Altered target (target enzyme has reduced affinity to antibacterial)
- Altered uptake
- – Increased efflux (mechanism developed to actively pump drug out of bacterium)
- – Decreased permeability to drug
11
Q
What is the genetic basis of drug resistance?
A
- Chromosomal gene mutation (natural selection!)
- Horizontal transfer (using plasmids)
